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ITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 775 

Contribution from the Bureau of Chemistry 
CARL L. ALSBERG, Chief 



Washington, D. C. 



June 3, 1919 



COMMERCIAL PRESERVATION OF EGGS 
BY COLD STORAGE 



By 

M. K. JENKINS, Assistant Bacteriologist. Prepared 

under the direction of M. E. PENNINGTON, Chief, 

Food Research Laboratory 



CONTENTS 



Pago 
Some Aspects of the Cold Storage Busi- 
ness 1 

Purpose of Investigation 2 

Genera! Plan of Investigation .... 2 
Results of Investigation : 

Effect of Condition of Shell Upon 

Preservation 5 

Relation of Quality to Preservation . 9 
- Commercial Grading for Storage . 10 
Relation of Month of Storage to 
Number of Bad Eggs in Cold 
Storage Firsts and Seconds . . 12 



Page 



Results of Investigation — Continued. 
Condition of Commercial Packages 

as Stored 16 

Analysis of Bad Eggs in Commercial 

Firsts and Seconds After Storing . 18 
Carefully Prepared Packages ... 20 
Shrinkage of Eggs and Absorption of 

Moisture by Case and Fillers . . 23 
Physical and Chemical Changes in 

Eggs During Storage 28 

Absorption of Foreign Flavors During 

Storage 33 

Summary 34 




WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1919 




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LIBRAE 0! .*» 

RECBWED 

JAN261921 

DOCUMENTS DIVISION 






^& 



UNITED STATES DEPARTMENT OF AGRICULTURE 




BULLETIN No. 775 



Contribution from the Bureau of Chemistry 
CARL L. ALSBERG, Chief 




Washington, D. C. 



June 3, 1919 



COMMERCIAL PRESERVATION OF EGGS BY COLD 

STORAGE. 1 

By M. K. Jenkins, Assistant Bacteriologist. Prepared under the direction of M. E. 
Pennington, Chief, Food Research Laboratory. 



CONTENTS. 



Some aspects of the cold storage business 1 

Purpose of investigation 2 

General plan of investigation 2 

Results of investigation: 

Effect of condition of shell upon preserva- 
tion 5 

Relation of quality to preservation 9 

Commercial grading for storage 10 

Relation of month of storage to number of 
bad eggs in cold storage firsts and 

seconds 12 

Condition of commercial packages as 
stored 16 



Page. 
Results of investigation— Continued. 

Analysis of bad eggs in commercial firsts 

and seconds after storing 18 

Carefully prepared packages 20 

Shrinkage of eggs and absorption of 

moisture by case and fillers 23 

Physical and chemical changes in eggs 

during storage 28 

Absorption of foreign flavors during 

storage 33 

Summary 34 



SOME ASPECTS OF THE COLD STORAGE BUSINESS. 

The preservation of eggs by means of cold renders one of the most 
important of the perishable foods available at all times. According 
to Holmes, 2 about 50 per cent of the egg crop is produced during 
the months of March, April, May, and June, and 86 per cent of the 
eggs held in storage are stored in March, April, and May. During 
these cool months the eggs are the freshest and most desirable for 
storing. According to a statement issued by the Bureau of Markets, 
April 15, 1918, 478 warehouses, which report holdings of eggs in 
cold storage, are fairly well distributed over the United States. 
The March 11, 1918, summary report, issued by the Bureau of 
Markets, shows that a total of 6,595,850 30-dozen cases, valued at 
$70,487,212, were stored in 396 houses during the season of 1917-18. 
These figures, although lower than the actual amounts, due, as men- 
tioned in the reports, to the failure of a few houses to forward state- 

1 The work covered in this bulletin was done in the Bureau of Chemistry. In the future, the market- 
ing phases of the Department's work on poultry and eggs will be conducted by the Bureau of Markets, 
under a cooperative arrangement with the Bureau of Chemistry. 

2 U. S. Dept. Agr., Statistics Bui. 93. 

99369°— 19— Bull. 77-5 1 



2 BULLETIN 775, TJ. S. DEPARTMENT OE AGRICULTURE. 

raents of their holdings, give a fair approximation of the extent and 
value of the business. 

The deliveries in appreciable quantities of eggs from cold storage 
begin in August, continue in increasing amounts during the fall and 
early winter months, and gradually decrease from this period until 
the first of March, when there are but few, or practically no eggs 
left in storage in normal seasons. For example, during the season 
of 1916-17 57.7 per cent of the holdings were left in storage on 
November 1, 34.2 per cent on December 1, 13.8 per cent on January 1, 
2.1 per cent on February 1, and 0.1 per cent on March l. 1 These 
statistics agree with those collected by Holmes 2 several years earlier. 
The increase in consumption of cold storage eggs during the winter 
corresponds to the marked decline in egg production during that time. 

PURPOSE OF THE INVESTIGATION. 

Although 'a number of publications discuss the losses in eggs which 
follow the routine course of marketing without the intervention of 
cold storage, 3 comparatively few data, showing the changes and losses 
in different grades of eggs handled according to commercial usages 
during various holding periods in cold storage, are available. This 
investigation was made primarily to determine the efficiency of the 
preservation of commercial eggs by cold storage. The following 
phases of the problem were studied: 

(1) The relative keeping quality of fresh, heated, sound, dirt} 7 , 
and cracked eggs. 

(2) The relation of the month of storage to preservation. 

(3) Efficiency of the commercial grading of eggs for cold storage. 

(4) Analysis of bad eggs developing in commercially packed eggs 
during storage. 

(5) Relation of care in initial grading to the development of bad 
eggs during storage. 

(6) Rate of evaporation of moisture from eggs. 

(7) Rate of absorption of .moisture by case and fillers. 

(8) Physical and chemical changes in eggs during storage. 

(9) Absorption of foreign flavors during storage. 

GENERAL PLAN OF INVESTIGATION. 

The eggs used in these observations were produced in the Corn 
Bolt States of the Middle West, with the exception of a few lots 
which came from Kentucky. They were shipped East in refrig- 
erator cars, and were from three to seven days en route. As soon 

1 Report of the Bureau of Markets issued Apr. 1, 1917. 

2 U. S. Dept. Agr., Statistics Bui. 93. 

s (J. 8. Dept. Agr. Buls. 51, 221, 664; U.S. Dept. fcgr., Bur ('hen:. Gircs. 83, KM; U. S. Dept. Agr., Year- 
book (1910) Article 552, and Yearbook (1914) Article 647. 



PRESERVATION OF EGGS BY COLD STORAGE. 3 

as received they were transferred to a commission house equipped 
with chill rooms, a candling and breaking room, all of which were 
refrigerated. Here the observations were made before the eggs were 
stored, as well as on removal from storage at various intervals during 
the storage period. The examination of the different classes of eggs 
to determine the relative deterioration consisted in determining the 
quality of the eggs in the shell by candling and out of the shell by 
appearance, odor, and chemical analysis. It was necessary to grade 
the eggs after they were opened because there are certain classes 
of bad eggs that can not be recognized and others which are fre- 
quently missed by grading in the shell. 1 The method of separating the 
edible and inedible eggs by candling 2 and breaking 3 was the same 
as that followed commercially in up-to-date candling and breaking 
rooms. The inedible eggs detected by candling correspond to those 
found by the dealers in grading eggs for market, and the bad eggs 
detected by breaking represent those that would be found when 
the eggs were opened by the consumer. Samples for laboratory 
examination were taken from the liquid product obtained on mix- 
ing the eggs graded as edible. Observations were made on 9 lots 
which were received and stored in New York City, and on 12 
lots delivered to and stored in Philadelphia. The eggs were stored 
at a temperature of from 30° to 33° F. in rooms used commercially 
for the cold storage of eggs in the shell (PL I). During this inves- 
tigation 841 30-dozen cases of eggs of varying grades were exam- 
ined before and after storing. The history of the different lots 
under observation is reported in detail in Table 1. 

i U. S. Dept. Agr. Bui. 702. 2 U. S. Dept. Agr. Bui. 565. » U. S. Dept. Agr. Bui. 391. 



BULLETIN 775, U. S. DEPARTMENT OF AGRICULTURE. 



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PKESEKVATION OF EGGS BY COLD STORAGE. 5 

RESULTS OF THE INVESTIGATION. 

EFFECT OF CONDITION OF SHELL UPON PRESERVATION. 

The losses in commercial fresh eggs with clean, sound shells were 
found to be negligible during a storage period of 11 months. In the 
experiment reported in Table 2 and figure 1, the bad eggs detected by 
candling and breaking did not amount to more than five eggs per case 
at any time during the storage period. The principal types of bad 
eggs found were green whites, crusted yolks, moldy eggs, mixed 
rots, and white rots (Table 3). The first two types mentioned are 
characteristic of washed eggs after storing. Unfortunately it is not 
possible to detect all washed eggs by inspection of the shell before 
storing. 

If the shell of a fresh egg is dirty its liability to spoilage during 
holding in cold storage is markedly increased. A typical lot stored 
in April showed on monthly withdrawals from storage from Septem- 
ber to March, inclusive, from 12 to 30 bad eggs per case by candling 
and from 10.5 to 29 additional by breaking (Table 2 and fig. 1). 
Among commercial dirty eggs are found eggs soiled with feces, mud, 
and blood, as well as stained eggs showing evidence of having been 
washed or having come in contact with the wet, muddy feet of hens 
or wet nests. Bacteria and molds can penetrate wet shells, even 
though unbroken, and cause the egg to rot. Moldy eggs, green 
whites, crusted yolks, mixed rots, white rots, and black rots are the 
principal varieties of bad eggs among dirty refrigerator eggs (Table 3). 

It is generally known that eggs with damaged shells will not keep 
in storage. This is strikingly shown in Table 2 and figure 1. The 
most common form of deterioration of the cracked egg is through 
molding, which, in stocks stored in spring, becomes pronounced in 
September and October, and increases throughout the storage period 
(Table 4). The bad eggs developing in cracked eggs stored in April 
and May varied, as found by candling and breaking, from 44 per 
case in September to 144 per case in March. If the shells were 
dirty in addition to being cracked, the losses were greater, amounting 
in eggs stored in April and held until December to as high as 211 to 
the case as found by candling (Table 2 and fig. 1). These observa- 
tions were made on damaged eggs present in first-grade commercial 
packages through oversight or carelessness during the initial sorting 
of the eggs for storage. The losses found would have been higher 
had the observations been made on cases containing only cracked 
eggs, for the mold growing on one egg readilv spreads to other broken 
eggs (PI. II). 

These studies emphasize the importance of selecting only eggs with 
clean, sound shells for storing. 



BULLETIN 115, U. S. DEPARTMENT OF AGRICULTURE. 






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BULLETIN 775, U. S. DEPARTMENT OE AGRICULTURE. 




Fig. 1. — Effect of condition of shell upon preservation of fresh eggs. 



Bui. 775, U. S. Dept. of Agriculture. 



Plate I. 

t» 




Cold-Storage Room, Showing Brine Coils and Stacks of Storace- 
Packed Eggs. Capacity, 4,000 Cases, or 1, 440, COO Eggs. 



Bui. 775, U. S. Dept. of Agriculture. 



Plate 1 1 . 




Upper layer. 




Lower layer. 
CONTAMINATION OF NEIGHBORING EGGS BY A MOLDING LEAKER. 



PRESERVATION OF EGGS BY COLD STORAGE. 



9 



RELATION OF QUALITY TO PRESERVATION. 

The initial quality of the eggs influences to a large extent their 
preservation by cold storage. Stale, weak, and hatch-spot eggs, 
which are only too plentiful in eggs marketed in the summer, lose 
heavily after a few months holding in cold storage. In the experi- 
ment cited in Table 5 and figure 2, the stale and heated eggs stored in 
July developed comparatively few bad eggs up to September, but 
from then until the end of March the loss was from 13.5 to 24 eggs 
per case by candling, with 9.5 to 19 additional by breaking. The 
number of bad eggs developing may be higher or lower than that 
found in this experiment, depending upon the degree of deterioration 
before the eggs entered storage. The most frequent types of bad 
eggs present in heated stock after storing are those with slightly 
stuck or broken-down yolks in various stages of addling. These eggs 
in the early stages are a form of mixed rot and are classed as such in 
Table 3. 

Table 5. — Relation of quality of clean eggs to preservation. 





Fresh eggs with clean, 
sound shells. 


Stale and heated eggs 
with clean shells. 


Stale and heated eggs 
with damaged shells. 


Month, of withdrawal. 


Eggs 
ob- 
served. 


Bad eggs per 
case. 


Eggs 
ob- 
served. 


Bad eggs per 
case. 


Eggs 
ob- 
served. 


Bad eggs per 
case. 




Can- 
dling. 


Break- 
ing. 


Can- 
dling. 


Break- 
ing. 


Can- 
dling. 


Break- 
ing. 


April 


1,026 





0.5 














May 














June '■ 
















July L. 




977 
949 
938 
949 
901 
954 
960 
926 
• 946 




8 

6 

2.5 
13.5 
14.5 
14 
24 
23 




4 

9 

4.5 

9.5 
10.5 
14 

12.5 
19 


90 
104 
106 
111 
109 

94 
100 
129 

96 




58 

64 

83 

135.5 
175 
147.5 
232.5 
251 


4 


August 






3.5 


September 


710 
704 
695 
709 
694 
715 
717 




1 

0.5 

0.5 



1 

2.5 


2.5 

1.5 

2 

1 

2.5 

2 

2.5 


20.5 


October 


32 


November 


33 


December 


11.5 


January 


18 


Februarv 


19 


March . 


15 











It does not follow, however, that because many of the eggs marketed 
in the summer months are shrunken and heated and do not keep well 
in storage, the eggs as laid by the hen in the summer are not initially 
as good in quality as those laid in the spring. Fresh hennery eggs 
laid in April and July, delivered to storage within approximately 48 
hours after being laid, showed a negligible loss in bad eggs, even after 
a long period of storage (Table 6). The bad eggs present were those 
showing a slight breaking down of the yolk. No eggs with green 
whites or crusted yolks were found. Their absence was to be ex- 
pected, because the natural condition of the shell had not been 
disturbed through soiling, washing, or contact with damp surround- 
ings. The good results in this report show the improvement yet to 
be attained in the commercial marketing of summer eggs. 
99369°— 19— Bull. 775 2 



10 BULLETIN 775, U. S. DEPARTMENT OE AGRICULTURE. 

Table G. — Relative keeping quality of freshly laid April and July hennery eggs. 



April hennery eggs. July hennery eggs. 


Months in 
storage. 


Number 
observed. 


Bad eees Months in 
oaa eggs. | storage< 


Number 
observed. 


Bad eggs. 


7.2 
11 


351 
274 


2 6.5 

2 8.5 

10.8 


275 
267 
241 


1 
2 










After holding from four to eight months'stale and heated cracked 
eggs stored in July showed a total of 168.5 to 266 bad eggs per case 
(Table 5 and fig. 2). The higher loss in these eggs, in comparison 
with the clean, cracked fresh eggs stored in the spring, may no doubt 
be explained by the development of larger numbers of molds and 
bacteria during the warm weather before storing. 

In short, these studies show that, for successful preservation, eggs 
to be stored for several months should have clean, sound shells, and 
be fresh in quality. 



COMMERCIAL GRADING FOR STORAGE. 



Most of the grading of eggs for storage is done in the producing 
sections, although some ungraded current receipts reach the markets 
in the consuming centers^ particularly from shippers located in the 
undeveloped poultry and egg sections of the country. It is generally 
recognized by the industry that only the best eggs should be used for 
storing, and that more care should be taken in the packing of eggs for 
storing than for direct marketing. New cases and new medium 
fillers (3 pounds 3 ounces per case) ordinarily are used. A very 
small proportion of the eggs are candled before storing, except in the 
summer when the production is light and the percentage stored small. 
The usual procedure is to sort the current receipts into various grades 
by clicking and inspecting the shells. From the case of current re- 
ceipts the sorters take in each hand three eggs, which, by an inward 
movement of the index finger, they click together (Plate III). 
A clear ring indicates whole shells; a deadened sound signifies the 
presence of cracked eggs. The latter are sorted into cases by them- 
selves, as are also the small and dirty eggs. These eggs are marketed 
for immediate consumption, or are broken and frozen in cans to be 
used by bakers as needed. Sometimes a grade called " trade eggs," 
sold principally in southern markets, is made from the clean, small 
eggs. The large eggs with clean, whole shells are used in the storage- 
packed eggs. Usually two grades, firsts and extra firsts, are prepared. 
The former must weigh at least 42 pounds to the case, and the lat- 
ter 44 pounds. The making of four grades from current receipts is 
shown in Plate IV. 

The sorting is done by either men or women, who are frequently 
inexperienced. Usually the work is directed by a foreman more or 
less skilled in egg handling and grading. 



PRESERVATION OF EGGS BY COLD STORAGE. 



11 




yytt/i-sot wp &/& t£^. 



1 £ 



s 5 



Fig. 2. — Relation of quality of clean eggs to preservation. 



12 BULLETIN 775, U. S. DEPARTMENT OE AGRICULTURE. 

RELATION OF MONTH OF STORAGE TO NUMBER OF BAD EGGS IN COLD STORAGE 

FIRSTS AND SECONDS. 

"Market firsts/' commercially packed for storage in April, May, 
June, and July, were studied for three consecutive seasons. It may 
be seen from Table 7 and figure 3 that the April and May commercially 
packed eggs showed a low number of bad eggs more uniformly during 
the course of the storage period than did the June and July commercial 
stocks. This may be accounted for by the fact that most of the 
spring eggs on the market are fresh, are not shrunken, and have not 
been exposed to high temperatures before storing. Some of the com- 
mercial summer firsts, for example, Experiments 41782, 41941, and 
41787, contained no more bad eggs after storing than did the com- 
mercial spring firsts. On the other hand, Experiments 41918, 41922, 
and 41945 showed heavy losses, even after a comparatively short 
period of storage. Indeed, it would not pay to carry such low-quality 
eggs in storage longer than the fall months. In commercial practice 
very few eggs are stored in summer, and practically all are withdrawn 
by November or December. In fact, in the summer when the general 
supply is poor in quality, dealers frequently draw from the spring 
stock in storage to fill orders requiring eggs of good quality. 

On withdrawal from storage between November and March, com- 
mercial spring and high-grade summer firsts showed usually from 12 
to 18 bad eggs per case by candling, with from 2 to 6 additional by 
breaking. On the other hand, summer seconds and low-grade com- 
mercial summer firsts, when withdrawn from storage between No- 
vember and March, ordinarily contained from 18 to 42 bad eggs per 
case, as determined by candling, and from 6 to 12 more as found by 
breaking (Tables 7 and 8 and fig. 3). 

Undergrade eggs, consisting of those which are dirty, small, 
shrunken, and heated, usually are r marketed directly in the shell or 
used in the preparation of frozen and dried products. These grades t 
of eggs are very seldom stored, except for short intervals, as the industry 
realizes that they do not keep well in storage for long periods. It is 
frequently convenient for the management of egg-breaking plants to 
buy large quantities of seconds in the spring when eggs are plentiful 
and cheap, to store for one or two months, and to open when the 
supply of these eggs on the market is short and when otherwise the 
breaking room would be practically idle. This practice is warranted 
only for very short intervals. There may be no appreciable increase 
in bad eggs during a storage period of four or five months, but the 
general quality is much lower because of increased staleness and 
higher bacterial content. 1 Because deterioration has already begun, 
summer seconds should not be stored, even for short periods; they 
should be sold for immediate consumption or promptly broken 
and frozen. In short, for successful preservation in storage in the 
shell, eggs, like other perishable products, must initially be in prime 
condition. • 

i Unpublished results. 



PRESERVATION OF EGGS BY COLD STORAGE. 



13 




BAD fG&F B>* ~C4A/DL/N&~X/\f{> BREAK/NO 



— -«- qao. SGG<3 By CAA/DUNG 

Fig. 3.— Increase in bad eggs per case in refrigerator firsts during storage. 



14 



BULLETIN 775, TJ. S. DEPARTMENT OP AGRICULTURE. 



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15 



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16 BULLETIN 775, TJ, S. DEPARTMENT OE AGRICULTURE. 



CONDITION OF COMMERCIAL PACKAGES AS STORED. 

Most warehouses require an examination of the cases of eggs for 
mechanical damage before permitting them to be taken to the cold- 
storage rooms, the thoroughness of the examination depending upon 
the strictness of the management. The officials of some warehouses 
demand that representative portions of carload lots be inspected, 
while others ask that each case be examined. In some cold-storage 
plants the examinations are made by the employees; in others, by the 
patrons. In the latter instance some firms exercise more care in 
inspection than the rulings of the warehouse require. In the ware- 
house where the eggs used in these investigations were stored, each 
patron examines his eggs and usually every case is opened. The top 
layers of each case are examined without being removed (PI. V, fig. 1), 
or they are lifted from the case and both the upper and lower sides 
examined (PI. V, fig. 2 and PL VI, fig. 1). When evidences of broken 
eggs are found in the top fillers (PL VI, fig. 2) each layer is inspected, 
and all leaking eggs discovered are replaced by eggs with whole shells 
in dry fillers. If no breakage is found in the top layers the remaining 
layers are undisturbed. 

The cases of eggs under observation were inspected according 
to the system shown in Plate V, figure 2, and Plate VI, figure 2. 
These cases, then, represented the condition of commercial packages 
on entering storage. The eggs were next candled to determine 
quality and to ascertain the number of dirty, cracked, leaking, and 
bad eggs included with the good, clean eggs. Representative 
samples were also broken to further discover the quality and to 
find the number of bad eggs rfot recognized by candling, and 
samples of* the liquid edible product were prepared for chemical 
analysis (Table 9, "Eggs as stored", and Tables 12 and 13). 



Bui. 775, U. S. Dept. of Agriculture. 



PLATE I I I 




Grading Eggs for Cold Storage by Inspecting and Clicking the 

Shells. 



Bui. 775, U. S. Dept. of Agriculture. 




Bui. 775, U. S. Dept. of Agriculture. 



Plate V. 




Bui. 775, U. S. Dept. of Agriculture. 



Plate VI 




PRESERVATION OF EGGS BY COLD STORAGE. 



17 



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.Q93fi9°— 19— Bull. 775- 



18 BULLETIN 775, U. S. DEPARTMENT OF AGRICULTURE. 

The number of bad eggs found by candling among commercial 
spring firsts before storing averaged from 0.5 to 2 eggs per case, as 
compared with. 1.5 to 10 eggs per case in the summer packed firsts. 
As would be expected, the initial number of bad eggs in the summer 
seconds was higher, averaging from 8.5 to 21.5 per case in the different 
lots (Table 9). The bad eggs found by candling could not have been 
recognized by sorting, that is, by visual inspection and clicking of 
shells ; therefore, their presence did not reflect upon the accuracy of the 
initial sorting, but upon the inadequacy of the system as compared 
with candling. The additional bad eggs found by breaking, consisting 
mostly of green whites, averaged from 0.5 to 4.5 eggs per case in the 
spring and summer supply. The condition of these eggs, not recog- 
nizable by candling, would not be discovered in the routine market- 
ing until opened by the consumer. 

The number of cracked eggs averaged from 14.5 to 29 per case 
in the storage packed firsts, and from 20 to 34 per case in the summer 
seconds. The leakers averaged from none to 3 per case in the 
different lots studied, showing that the absence of damage in the top 
la}rers, as determined by commercial inspection, does not always 
indicate that there is none in the lower layers. The findings here 
corroborate the more extensive investigations made by Pennington, 
McAleer, and Greenlee. 1 

Some lots of storage packed firsts contained but few dirty eggs; 
others snowed an average of 30 eggs per case. The presence of dirty 
eggs in commercial packages may be attributed directly to oversight 
or carelessness in the initial sorting of the eggs for storage. 

ANALYSIS OF BAD EGGS IN COMMERCIAL FIRSTS AND SECONDS AFTER STORING. 

Studies were made to determine the relative number of bad eggs 
developing in storage from whole, cracked, and leaking eggs present 
in the commercial storage stocks. These observations were based 
on spring and summer eggs withdrawn at monthly intervals from 
November until March, inclusive. Three cases of each lot were 
examined monthly, but, for simplicity, the results for the entire 
period are averaged. It was observed that most of the bad eggs 
developing in storage packed eggs were evident by November. 

As might be expected, a large portion of the cracked eggs originally 
present in the commercial packages spoiled during storage (Table 9, 
"Bad eggs after storing/' and figs. 4 and 5). Out of the average 
of from 15 to 19.5 cracked eggs per case present when the commercial 
spring firsts entered storage, from 4 to 9 bad eggs per case developed, 
as detected by candling, and from 0.5 to 1.5 additional per case as 
found by breaking. The losses were still higher in the summer packed 
firsts. For example, Experiment 41945 when stored contained an 

i TJ. s. Dept. Agr. Bui. 664. 



PRESERVATION OF EGGS BY COLD STORAGE. 19 

average of 20 cracked eggs per case, of which 8 were found to be 
inedible after storing. Practically all of the leaking eggs spoiled by 
molding. 

Damaged eggs, particularly leaking eggs, in becoming moldy may 
contaminate neighboring eggs and cause them to spoil. When the 
contents of a broken egg leak out and soak into a strawboard filler, 
the filler usually becomes moldy, and causes eggs coming in contact 
with it to mold. This contamination may extend to eggs in adjoining 

j4jD/?/£ r//?S7S (sTX/? 4/S33) \O.S ES 6 ^ Hi 3 

AZ4y /^//?STS (fX# <?/&3G) \o.S WR 7 " H S 



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iJVLy /70S7& (£X/? '4/A?-?J ■/<? ■■?©• ■<?<? 





ist/tr /vasts i£x/?4/9#s) B- 3 - 5 " jgBMBBHm 30 

Fig. 4.— Analysis of bad eggs in refrigeration firsts, commercially packed (data given as bad eggs per 

case from Table 9.) 

pockets or through flats to the eggs beneath. Plate II illustrates an 
aggravated case of the spoilage which may result from the presence 
of only one badly broken egg in the case. In the different lots of 
eggs studied, an average of from 1 to 4 eggs with sound shells per 
case was spoiled by leaking eggs. 

Dirty eggs constituted but few of the bad eggs present in the com- 
mercially packed firsts. As found by candling, the bad eggs with 
dirty shells averaged from none to 2.5 eggs per case in the different 
lots examined. 

/ACt/QA7Z0/tjGS,f7C.. HMSwm SrM£&, M£4rf£>. COV7X/ftV4r/r£> SGCS. 

^6Wfs/wi/£/y/?rrf<?<?s(fx/?<K9/<s) 

k/(/A/£~ £>//?fr fees (£X/?4/343) 
JC/Ly SfCO/VOS (fX&<?/S23) 

Fig. 5.— Analysis of bad eggs in refrigerator seconds, commercially packed ( data given as bad eggs per 

case from Table 9.) 

The clean eggs with sound shells constituted the majority of the 
eggs in the commercial cold storage firsts. In the spring stocks these 
eggs furnished an average of from 2 to 7 bad eggs per case, as found 
by candling, and an average of 4 extra, by breaking. In the summer 
stocks they contributed an average of 4.5 to 17 bad eggs per case by 
candling, and 6.5 to 10.5 additional by breaking. The inedible eggs 
in the clean summer seconds with sound shells, as found by candling 
and opening, were practically the same in number as the poorer 
grade of summer firsts. A large proportion of the bad eggs in the 




20 BULLETIN 775, U. S. DEPARTMENT OF AGRICULTURE. 

spring firsts with whole shells may be attributed to the presence of 
eggs which at some time previous to storage had had wet shells, 
because of washing -the eggs or for some other reason. If the dirt is 
left on the shells the eggs can be graded accordingly, but if washed it 
is not always possible to differentiate between them, with the result 
that washed eggs are frequently graded as firsts. Washed eggs do 
not keep as well as dirty eggs. Attempts, therefore, to improve the 
appearance of dirty eggs by washing is a practice which can not be 
too strongly condemned. In eggs stored from summer production 
there is an additional loss due to the physical breaking down of the 
egg contents as a result of exposure to warm temperatures before 
storing. 

These studies show that the following factors are responsible for 
the development of a large percentage of bad eggs in commercial 
spring firsts during storage : (1 ) Inaccuracies in the system of sorting 
eggs for storage; (2) the inadequacy of that system in determining 
quality and detecting bad eggs; and (3) to a lesser extent, damage 
during the railroad haul. The bad eggs developing during storage 
in the summer stocks are due to these factors, combined with a lower 
initial quality. 

CAREFULLY PREPARED PACKAGES. 

In order to determine the relation between care in initial grading 
and the number of bad eggs developing during storage, packages 
containing as far as possible only good eggs with clean whole shells 
were prepared from each lot of commercially packed eggs studied 
during the last two seasons of the investigation. To determine quality 
and to eliminate bad eggs, the eggs were selected by candling instead 
of by simply inspecting and clicking the shells. 

Candling is a more accurate method for the detection of cracked 
eggs than is the clicking of shells, as ordinarily practiced. Enough 
carefully graded packages were prepared so that one case could be 
withdrawn monthly from storage with each three cases of correspond- 
ing commercially packed eggs. Following such a procedure, the 
carefully packed eggs, excluding Experiment 41897, contained an 
average of three cracked eggs per case after carting from the com- 
mission house to the cold storage warehouse and return. Of this 
number from one to two of the cracked eggs may be accourted for by 
handling error in putting up the eggs for storage, and the balance by 
damage during cartage. The number of cracked eggs in Experiment 
41897 was unusually high, largely because of the use of a very poor 
grade of filler, so that more damage than usual was incurred during 
cartage. 

Table 9 and figures 6 and 7 show that the number of inedible eggs 
present after storing was reduced in the carefully packed, as com- 
pared with the commercial cases. In the April and May refrigerator 



PRESERVATION OF EGGS BY COLD STORAGE. 



21 



firsts there was an average of 13.5 inedible eggs per ease found by can- 
dling in the commercially packed eggs, as compared with 4 in those 
carefully packed. These figures are the averages of the resuli- si 
monthly observations made from November to March. Figuring the 
value of eggs when stored in the spring of 1917 as 35.6 1 cents per dozen, 
and charging 3 cents a dozen to cover insurance, interest, and carrying 
cost, there was an average money loss in bad eggs in the commercially 
packed eggs of 43.5 cents, as compared with 13 cents per case in those 

CO/W£GC/A/./.r pac/ted cAP£ruu.y packed 
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Fig. 6. — Relation of care in initial sorting to number of bad eggs in refrigerator firsts (data given as bad 

eggs per case from Table 9). 

carefully packed. An average of 11 cracked eggs, which were still 
good by candling, was found in the case of the commercially packed 
eggs . These, however, on account of their impaired shells, would bring 
one- third less on the markets than their companion eggs with good 
shells, making a further additional loss of 12 cents per case. The total 
loss, then, in the commercial stocks averages 55.5 cents*per case, as 
compared with 13 cents in the carefully packed eggs. It costs about 
5 cents more per case to grade by candling than by sorting. Even 



i U. S. Dept. Agr., Bureau of Markets Report of Mar. 11, 1918. 



22 



BULLETIN 775, TJ. S. DEPARTMENT OF AGRICULTURE. 



with, this added expense there was a saving of 37.5 cents per case in 
favor of the carefully packed eggs which amounts to $140 per carload 
of 400 cases in spring stocks stored until after November. 

In the summer commercial firsts and seconds careful packing did 
much to reduce the number of bad eggs developing during storage, 
but it did not offset the losses due to the lower initial quality of the 
entering material (Table 9 and fig. 7). 

It is believed with a little attention given to the checking of the 
accuracy of the sorting of eggs for storage, the number of cracked 
and dirty eggs missed could be greatly lessened without materially 
reducing the amount of work accomplished. In addition, since the 
detection of cracked eggs depends upon hearing distinctly the sound 
emitted on tapping the eggs together, noises in the work room should 
be eliminated as far as possible. Far greater efficiency, however, 

\ey &s 






OLsS 







xSOZ.r S£CQM2$(£X#«&&23) 




/&.& 
&& 







Fig. 7. — Relation of care in initial sorting to number'of bad eggs in refrigerator seconds (data given as bad 

eggs per case from Table 9). 

would be obtained by candling all eggs entering storage. Realizing 
the importance of having a uniformly graded product, some of the 
more progressive western houses make a practice of candling all eggs 
stored, at the same time enforcing a checking system x to see that the 
work is accurately done. This is a big step forward, for by candling 
the cracked eggs can be more accurately eliminated, and low quality 
and bad eggs may be detected and discarded. Under such a system 
the graders become so skilled that their work is as accurate as that of 
the carefully packed stocks of this investigation. 

Such eggs, being practically free from mold after several months 
in storage, are an advertisement to the firm selling them, and in 
practice it has been found that their more uniform quality has 
secured for them special outlets with higher prices. According to 
the present system of marketing, storage packed eggs may pass 
through several hands before they are finally consumed, with the 



i U. S. Dept. Agr. Bui. 702. 



PRESERVATION OE EGGS BY COLD STORAGE. 23 

result that the original shipper seldom sees the condition of his goods 
when they are withdrawn from storage. For example, the packer 
in the producing section may sell to a commission man in the East, 
who in turn may sell to another dealer. Upon withdrawal from 
storage the eggs may go into another buyer's hands before they are 
finally graded for the retail market. In addition to buying accord- 
ing to shrinkage before the candle and weight, dealers in storage 
packed eggs should demand that the cases be practically free from 
cracked eggs. This factor has received too little attention in the 
past, taking into consideration the fact that the average of 19 cracked 
eggs per case as the eggs leave the shipper's hand frequently furnishes 
half of the bad eggs developing during storage. In the final analysis, 
the original packer must bear the burden of expense of the stale, 
dirty, cracked, leaking, and bad eggs included in the storage grade, 
for, in order to play safe, buyers must pay a lower price for the whole 
package than they would if sure of receiving cases containing only 
large, clean, fresh eggs with whole shells. If there is no direct 
market for the cracked, dirt}', shrunken, and leaking eggs in the shell, 
their initial quality can be conserved by breaking and freezing in 
cans. Ordinarily there is a good market for frozen egg products 
of high quality. 

SHRINKAGE OF EGGS AND ABSORPTION OF MOISTURE BY CASE AND FILLERS. 

The changes in weight of eggs, case, and fillers were studied in 
three different storage rooms. All the weighings were made in the 
room where the eggs were held, because it was found that the cases and 
fillers frequently gained in weight if removed to a higher temperature. 
A sensitive scale was used. First the gross weight was found ; then 
the eggs were transferred to a second case, and the fillers and the 
case weighed. The net weight of the eggs was determined by differ- 
ence. After weighing, the eggs were returned to the original cases 
and fillers, so that the periodical weighings during the storage period 
were made on the same cases, fillers, and eggs. 

There was an almost regular decrease in the net weight of the eggs 
during the course of the storage period, amounting to an average of 4.48 
ounces per case per month for eggs stored in Room 1, and 3.46 ounces 
per month for eggs stored in Rooms 2 and 3. In Room 1 the decrease 
in the gross weight of a case of eggs weighing initially 56.84 pounds 
gross and 45.80 pounds net was 25.29 ounces and 38.20 ounces, 
respectively, during a storage period of 9.2 months. In Room 2 a 
case of eggs weighing 57.33 pounds gross and 45.01 pounds net at 
the beginning of the season lost 12.73 ounces gross and 26.14 ounces 
net after 9 months in storage. These typical results show, then, 
that attempts to determine shrinkage of eggs by finding changes in 
weight of the total package alone, a procedure frequently followed 
commercially, give misleading figures (Table 10 and fig. 8). 



24 



BULLETIN 775, U. S. DEPARTMENT OF AGRICULTURE. 



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25 



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26 



BULLETIN 775, U. S. DEPARTMENT OF AGRICULTURE. 




^v5 



Fig. 8.— Temperature, relative humidity, and amount of shrinkage of eggs in a case of 30-dozen capacity 
in Cold Storage Room 3 (data from Tables 10 and 11). 



PRESERVATION OF EGGS BY COLD STORAGE. 



27 



The amount of moisture absorbed by the fillers and case varied in 
different rooms and for different cases in the same room during the 
storage period. Probably most of the moisture absorbed is from the 
water evaporating from the eggs. Cases exposed to drafts from 
the outside, as through the opening of doors, would condense moisture 
from the incoming air, but under ordinary conditions the moisture 
coming from this source would be small in quantity compared with 
that derived from the eggs. Most of the moisture was taken up by 
the case and fillers during the first four or five months, and from this 
time on the weights usually showed a slight gain or remained prac- 
tically stationary. In Room 1 fillers having an initial weight of 3.61 
and 3.68 pounds gained 3.99 and 4.13 ounces, respectively, after 9.2 
months in storage ; and in Room 2 of two sets of fillers, each weighing 
3.7 pounds at the beginning, one gained 6.17 and the other 6.81 ounces 
in 9 months. In Room 1 cases weighing 7.74 and 8.16 pounds at the 
outset absorbed 4.73 and 3.10 ounces, respectively, of moisture in 9.2 
months; and in Room 2 of two cases each weighing 7.98 pounds, one 
gained 6.70 ounces and the other 7.80 ounces of moisture during 
practically the same period of time (Table 10 and fig. 8). 

The temperature of the three rooms in which these observations 
were made was quite uniform throughout the storage period. For 
example, in Room 3 the fluctuations in temperature were rarely more 
than 30° to 33° F., except during the severe winter, when the ther- 
mometer dropped to 28° F. and occasionally to 26° F. for a few hours. 
During most of the season the average temperature was 31° F. (Table 
11 and fig. 8). 

Table 11. — Average relative humidity and average temperature of Cold Storage Room 3. 



Week 
ending. 


Average 
relative 
humid- 
ity. 


Average 
tempera- 
ture. 


Week 
ending. 


Average 
relative 
humid- 
ity. 


Average 
tempera- 
ture. 


1917. 


Per cent. 


°F. 


1917. 


Per cent. 


°F. 


May 28 


74 


31 


Nov. 5 


83 


31 


June 4 


78 


31 


Nov. 12 


84 


31 


June 11 


76 


31 


Nov. 19 


85 


31 


June 18 


76 


31 


Nov. 26 


87 


31 


June 25 


76 


31 


Dec. 2 


88 


31 


July 2 


75 


31 


Dec. 9 


88 


31 


July 8 


74 


31 


Dec. 17 


88 


30 


July 16 


78 


31 


Dec. 24 


88 


30 


July 23 


78 


31 


Dec. 31 


89 


30 


July 30 


76 


31 


1918. 






Aug. 5 


75 


31 


Jan. 7 


89 


30 


Aug. 17 


77 


31 


Jan. 14 


89 


28 


Aug. 23 


72 


31 


Jan. 21 


87.5 


29 


Aug. 27 


73 


30 


Jan. 28 


80 


29 


Sept. 4 


77 


31 


Feb. 4 


89 


30 


Sept. 10 


80 


31 


Feb. 11 


90 


29 


Sept. 17 


82 


31 


Feb. 18 


90 


31 


Sept. 24 


83 


31 


Feb. 25 


91 


32 


Oct. 1 


83 


31 


Mar. 4 


91 


32 


Oct. 8 


84 


31 


Mar. 11 


91 


31 


Oct. 16 


82 


31 


Mar. 18 


91 


31 


Oct. 22 
Oct. 29 


81 

82 


31 
31 


Mar. 25 
Apr. 1 


91 
91 









28 BULLETIN 775, IT. S. DEPARTMENT OF AGRICULTURE. 

Table 1 1 and figure 8 give the average percentage relativ^ humidi- 
ties 1 by weeks in Room 3. The humidity from the beginning of the 
season up to September varied from 72 to 77 per cent, and from that 
time until the end of the season gradually increased to a maximum 
of 91 per cent. The cause of the rise in relative humidity in this 
room may be attributed to several factors: (1) Beginning with Sep- 
tember the doors were opened frequently on account of the removal 
of eggs from cold storage, thus allowing an inrush of air frequently 
laden with moisture; (2) during the early fall months the cases and 
fillers had become saturated with moisture for the temperatures at 
which they were held, so that they did not continue to assist ma- 
terially in the removal of moisture from the air; (3) by this time the 
brine pipes had become heavily frosted because of the condensation 
of moisture from the air, which rendered them less efficient both as 
absorbers of heat and as condensers of moisture; (4) after the warm 
weather of the summer had passed, less brine was circulated through 
the pipes, thereby reducing their efficiency as condensation agents; 
(5) with the advance of the season the number of cases decreased, so 
that there was more air in the room to carry moisture and less surface 
exposed for condensation and absorption. In this room, as well as 
in the other two rooms in which observations were made on the 
shrinkage of eggs, calcium chlorid was used as a drying agent. All 
three rooms were chilled by brine pipes on the walls. 

PHYSICAL AND CHEMICAL CHANGES IN EGGS DURING STORAGE. 

During the commercial holding of eggs in cold storage the air 
space increases in size because of the evaporation of moisture; the 
white becomes thinner and eventually loses its opalescence. After 
six or seven months the white usually develops a yellow tinge, which 
deepens with the length of the storage period. The clouded appear- 
ance of the white is especially noticeable when eggs are separated 
in large quantities, as is done in a commercial egg-breaking room. 
The slightly yellow color does not destroy the beating quality of the 
white nor the porcelain white color of the resulting froth. The yolk 
membrane weakens slowly, but, if the eggs are fresh on storing, most 
of them can be separated, even after storage for 11 months. The 
separation, however, is usually not as easy as in the earlier part of 

1 The determinations of relative humidities were made according to a sulphuric acid vapor pressure 
method by N. Hendrickson and H. C Woodward, which, in brief, was as follows: Two gram samples of 
sulphuric acid of concentrations varying from 15 to 35 per cent were allowed to come to equilibrium in the 
storage rooms in low, wide-mouth weighing bottles. The bottles were then covered, allowed to come to 
room temperature, and then weighed. The percentage of the sulphuric acid in equilibrium was calculated 
from the original concentration. The vapor pressure corresponding to the concentration of the sulphuric 
acid in equilibrium divided by the vapor pressure of saturated water vapor at 32° F. equals the percentage 
of the relative humidity of the air of the cold-storage room. The usual method of determining the relative 
humidity by a sling pschychrometer was not used, as it is not accurate at 32° F. and below, because of 
the freezing of the water on the wet bulb. 



PRESERVATION OF EGGS BY COLD STORAGE. 29 

the storage period. If the physical condition of the egg is weakened 
through being stale, or heated, or both, separation is difficult after 
being held in storage for only a few months. 

Accompanying the evaporation of moisture from the egg, Greenlee * 
found that there was a transfer of moisture from the white to the 
yolk by osmosis. For example, samples of whites and yolks, show- 
ing 87.42 per cent and 49.15 per cent moisture, respectively, after 
holding in storage for 41 days, contained 85.35 per cent and 50.60 
per cent, respectively, at the end of 266 days in storage. 

i U. S. Dept. Agr., Bur. Chem. Cir. 83. 



30 



BULLETIN 775, IT. S. DEPARTMENT OF AGRICULTURE. 



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PRESERVATION OF EGGS BY COLD STORAGE. 33 

The amount of ammoniacal nitrogen 1 in samples of April and May 
storage eggs graded as edible by candling and breaking was found to 
be initially from 0.0012 to 0.0021 per cent on the wet basis, and to 
increase gradually during storage to about 0.0030 per cent in Novem- 
ber or December, that is, the seventh or eighth month in storage, 
and to remain nearly stationary or even to rise slightly until the end 
of March, the close of the storage period (Tables 12 and 13). Sum- 
mer eggs entering storage with the same degree of freshness as the 
spring eggs showed practically the same increase during the same 
period of holding. In samples having a high initial percentage of 
ammonia, for example, Experiment 41923 in Table 13, the slowing 
down in the production of ammonia seemed to occur sooner than in 
the case of the better quality eggs. This may, perhaps, be explained 
by the chemical change which took place before the eggs were stored. 
The amount of ammoniacal nitrogen in the summer firsts and seconds 
was less consistent during the different months of storage than in the 
spring eggs. This may be explained by variations in quality between 
different cases in the same lot, a condition of frequent occurrence in 
summer shipments. There was very little difference in ammoniacal 
nitrogen in samples prepared from cracked eggs and those from eggs 
with whole shells sorted from the same lot. The evidence seems to 
show that even though the loss in unmarketable eggs varies with 
different classes, such as clean, dirty, and cracked eggs, if the eggs 
initially have the same interior quality, those that do keep show 
practically the same degree of preservation, judged by physical 
appearance and the amount of ammoniacal nitrogen present. 

Pennington, Hendrickson, and collaborators 2 found that during 
a storage period of six months there was no change in the dextrose 
in eggs, provided they were not infected with bacteria. In unpub- 
lished studies by these investigators, it was found that even up to 10 
months storage the dextrose content remained constant. 

ABSORPTION OF FOREIGN FLAVORS DURING STORAGE. 

It has been found that under commercial conditions a character- 
istic unpleasant flavor, commonly termed the "cold storage taste," 
develops in eggs which have been held in cold storage for several 
months. It is especially noticeable when the eggs are soft boiled or 
poached. The flavor is not as marked in the white as in the yolk 
which contains a large percentage of fat. It is known that fats 
have an affinity for odors and flavors. The facts indicate that the 
"cold storage taste" is due to the absorption of surrounding odors. 
When closed the storage room itself has some odor, as have also the 

1 The determinations of ammoniacal nitrogen in these samples were made by G. C. Swan, according to 
the methods described in the Journal of Industrial and Engineering Chemistry, Vol. 10, No. 8, p. 614, 
August, 1918, "Determination of Loosely Bound Nitrogen as Ammonia in Eggs," by N. Hendrickson 
and G. C. Swan. A forthcoming publication will give the bacterial findings, also determinations of ammo- 
niacal nitrogen in large numbers of individual eggs during various holding periods in cold storage. 

2 Jour. Biol. Chem. (1915) Vol. 20, p. xxi, Proceedings of the American Society of Biological Chemists. 



34 BULLETIN 775, U. S. DEPARTMENT OF AGRICULTURE. 

cases and excelsior, but the strawboard fillers and flats possess an 
odor more nearly resembling that found in storage eggs. The 
fillers and flats become slightly damp in storage, due to the absorption 
of moisture evaporating from the eggs and the air of the room, and 
acquire a stronger odor than when dry. Experiments which will be 
described in connection with another investigation show that when 
eggs are protected from air by immersion in a preserving liquid and 
held in cold storage, the typical "cold storage taste" does not de- 
velop. This shows almost conclusively that the " storage taste" is 
a foreign flavor absorbed by the eggs. 

Dirty and cracked eggs absorb this flavor more quickly and to a 
greater extent than do eggs with clean shells. Although summer 
eggs usually do not keep as well in storage as spring eggs, they are 
preferable in winter from the point of view of flavor, because they 
have not been held in storage as long as the spring eggs. A 
' - storage ' ' flavor can usually be found in April stock in November, 
in May eggs in December, in June eggs in January, and in July eggs 
in February. 

SUMMARY. 

(1) Practically all the eggs used in these investigations were pro- 
duced in the Middle West and all were stored in warehouses located 
in the East. 

(2) Freshly laid eggs with clean whole shells that have not been wet 
show a negligible loss in bad eggs, even after 10 to 1 1 months in storage. 

(3) Imperfections in commercial handling, grading, and marketing 
previous to storage are mainly responsible for the bad eggs developing 
in commercial eggs during storage. 

(4) The preservation in the shell of undergrade eggs, such as dirty, 
cracked, leaking, heated, and stale eggs, should not be attempted- 
If not marketed for prompt consumption, the contents should be re- 
moved under proper conditions and frozen. The frozen product will 
keep for a year or more, whereas there would be a marked de- 
terioration in quality, if the eggs were stored in the shell. 

(5) Spring eggs on the market are usually fresher than summer 
eggs, and for that reason keep better in storage. Most of the eggs 
stored are produced in the spring. 

(6) The commercial selection by inspection and clicking of clean 
eggs with sound shells from current receipts is inefficient. Commer- 
cial packages of spring firsts when ready to be taken to the storage 
rooms showed an average of 17.5 cracked eggs and 1 leaking egg to 
the case. Dirty and stained eggs were often included. Owing to 
the high quality of spring stock, there was usually less than 1 bad 
egg to the case initially present as found by candling. 

(7) Candling is a much more accurate method for the selection of 
eggs for storage. By this method eggs can be graded according to 



PRESERVATION OF EGGS BY COLD STORAGE. 35 

quality; cracked eggs can be more accurately detected and eliminated; 
and bad eggs can be found and rejected. Cases of spring firsts 
graded by candling did not average more than 3 cracked eggs per 
case when ready for storage. 

(8) Spring eggs prepared for storage by commercial sorting showed 
after 7 to 11 months' storage an average total loss of 18.5 bad eggs 
per case, 13.5 of which were detected by candling and 5 by breaking. 
Corresponding cases of eggs graded for storage by candling showed 
after a similar period in storage 4 bad eggs per case as found by 
candling and 3 additional by breaking. The value of the good eggs 
saved by the careful candling of eggs for storage more than offsets 
the extra cost of preparation. 

(9) Of the average of 18.5 bad eggs per case present in the com- 
mercially graded spring packages after long storing, 9 were due to 
direct spoilage of damaged eggs or to their contamination of neigh- 
boring eggs by molding. The deterioration of the balance of the 
eggs with whole shells was no doubt due to deleterious pre-storage 
conditions, such as dirty, wet, stained, or washed shells, or heated 
shell contents. Careful grading of eggs for storage very largely 
eliminates the loss due to damaged, dirty, or stained shells. 

(10) The rate of evaporation of moisture from eggs was remarkably 
uniform during the storage period, and averaged from 3 to 4 ounces 
per case per month in the different storage rooms under observation. 

(11) The moisture from the eggs is condensed on the brine pipes, 
and absorbed by the air, case, and fillers. Most of the absorption 
of moisture by the egg package occurs during the first few months 
in storage. In these studies the gain in weight of individual cases 
with the accompanying cushions, fillers, and flats varied from 11.5 to 
14 ounces during a storage period of 10.8 months. 

(12) In the cold-storage rooms under observation there was a 
gradual rise in the humidity with the advance of the season. 

(13) Eggs that are fresh when stored show after storing an in- 
creased air space and often a tinge of yellow in the white. The yolk 
membrane is slightly weakened, but commercial separation into white 
and yolk is usually easily accomplished, even after 11 months' storage. 

(14) The percentage of ammoniacal nitrogen in eggs increases 
during storage, the rise being the fastest during the early part of 
the storage period. The amount of ammoniacal nitrogen in eggs is 
a good index of chemical deterioration. 

(15) During commercial holding in cold storage the eggs develop 
a characteristic " cold-storage taste," which is usually present after 
the seventh month and becomes stronger the longer the eggs are 
stored. The evidence' seems to indicate that the flavor is due to the 
absorption of the odors from the surrounding environment, particu- 
larly from the strawboard fillers in which the eggs are packed. 



PUBLICATIONS OF THE U. S. DEPARTMENT OF AGRICULTURE RELATING 
TO THE PRODUCTION AND MARKETING OF EGGS. 

Natural and Artificial Incubation of Hens' Eggs. (Farmers' Bulletin 585.) 

Community Egg Circle. (Farmers' Bulletin 656.) 

Marketing Eggs by Parcel Post. (Farmers' Bulletin 830.) 

Bacteriological and Chemical Study of Commercial Eggs in Producing Districts of 

Central West. (Department Bulletin 51.) 
Study of Preparation of Frozen and Dried Eggs in Producing Section. (Department 

Bulletin 224.) 
How to Candle Eggs. (Department Bulletin 565.) 
The Installation and Equipment of an Egg Breaking Plant. (Department Bulletin 

663.) 
The Prevention of Breakage of Eggs in Transit When Shipped in Carlots. (Department 

Bulletin 664.) 
Efficiency of Commercial Egg Candling. (Department Bulletin 702.) 
Winter Egg Production. (Secretary's Circular 71.) 
Marketing Eggs Through the Creamery. (Farmers' Bulletin 445.) 
Shipping Eggs by Parcel Post. (Farmers' Bulletin 594.) 
Eggs and Their Value as Food. (Department Bulletin 471.) 
Variation in Annual Egg Production. (Bureau of Animal Industry Bulletin 110, 

pt. 1.) 
Seasonal Distribution of Egg Production. (Bureau of Animal Industry Bulletin 

110, pt. 2.) 
Improvement of Farm Egg. (Bureau of Animal Industry Bulletin 141.) 
Care of Farm Egg. (Bureau of Animal Industry Bulletin 160.) 
Preliminary Study of Effects of Cold Storage on Eggs. Quails, and Chickens. (Bureau 

of Chemistry Bulletin 115.) 
Bacteriological Study of Shell, Frozen, and- Desiccated Eggs, Made Under Laboratory 

Conditions at Washington, D. C. (Bureau of Chemistry Bulletin 158.) 
Deterioration of Eggs as Shown by Changes in Moisture Content. (Bureau of Chem- 
istry Circular 83.) 
Practical Suggestions for Preparation of Frozen and Dried Eggs, Statement Based on 

Investigations Made in the Producing Section During Summer, 1911. (Bureau of 

Chemistry Circular 98.) 
The Handling and Marketing of Eggs. (Yearbook Separate 467.) 
The Effect of the Present Method of Handling Eggs on the Industry and the Product. 

(Yearbook Separate 552.) 

o 

36 



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